itsybitsy-m4

Constants

const RESET_MAGIC_VALUE = 0xf01669ef

used to reset into bootloader

const (
    D0    = PA16    // UART0 RX/PWM available
    D1    = PA17    // UART0 TX/PWM available
    D2    = PA07
    D3    = PB22
    D4    = PA14    // PWM available
    D5    = PA15    // PWM available
    D6    = PB02    // dotStar clock
    D7    = PA18    // PWM available
    D8    = PB03    // dotStar data
    D9    = PA19    // PWM available
    D10    = PA20    // can be used for PWM or UART1 TX
    D11    = PA21    // can be used for PWM or UART1 RX
    D12    = PA23    // PWM available
    D13    = PA22    // PWM available
)

GPIO Pins

const (
    A0    = PA02    // ADC/AIN[0]
    A1    = PA05    // ADC/AIN[2]
    A2    = PB08    // ADC/AIN[3]
    A3    = PB09    // ADC/AIN[4]
    A4    = PA04    // ADC/AIN[5]
    A5    = PA06    // ADC/AIN[10]
)

Analog pins

const (
    LED = D13
)

const (
    USBCDC_DM_PIN    = PA24
    USBCDC_DP_PIN    = PA25
)

UART0 aka USBCDC pins

const (
    UART_TX_PIN    = D1
    UART_RX_PIN    = D0
)

UART1 pins

const (
    UART2_TX_PIN    = A4
    UART2_RX_PIN    = D2
)

UART2 pins

const (
    SDA_PIN    = PA12    // SDA: SERCOM2/PAD[0]
    SCL_PIN    = PA13    // SCL: SERCOM2/PAD[1]
)

I2C pins

const (
    SPI0_SCK_PIN    = PA01    // SCK: SERCOM1/PAD[1]
    SPI0_MOSI_PIN    = PA00    // MOSI: SERCOM1/PAD[0]
    SPI0_MISO_PIN    = PB23    // MISO: SERCOM1/PAD[3]
)

SPI pins

const (
    TWI_FREQ_100KHZ    = 100000
    TWI_FREQ_400KHZ    = 400000
)

TWI_FREQ is the I2C bus speed. Normally either 100 kHz, or 400 kHz for high-speed bus.

const (
    I2SModeMaster    I2SMode    = iota
    I2SModeSlave
    I2SModePDM
)

const (
    I2StandardPhilips    I2SStandard    = iota
    I2SStandardMSB
    I2SStandardLSB
)

const (
    I2SClockSourceInternal    I2SClockSource    = iota
    I2SClockSourceExternal
)

const (
    I2SDataFormatDefault    I2SDataFormat    = 0
    I2SDataFormat8bit            = 8
    I2SDataFormat16bit            = 16
    I2SDataFormat24bit            = 24
    I2SDataFormat32bit            = 32
)

const NoPin = Pin(-1)

NoPin explicitly indicates “not a pin”. Use this pin if you want to leave oneof the pins in a peripheral unconfigured (if supported by the hardware).

const (
    PinAnalog        PinMode    = 1
    PinSERCOM        PinMode    = 2
    PinSERCOMAlt        PinMode    = 3
    PinTimer        PinMode    = 4
    PinTimerAlt        PinMode    = 5
    PinTCCPDEC        PinMode    = 6
    PinCom            PinMode    = 7
    PinSDHC            PinMode    = 8
    PinI2S            PinMode    = 9
    PinPCC            PinMode    = 10
    PinGMAC            PinMode    = 11
    PinACCLK        PinMode    = 12
    PinCCL            PinMode    = 13
    PinDigital        PinMode    = 14
    PinInput        PinMode    = 15
    PinInputPullup        PinMode    = 16
    PinOutput        PinMode    = 17
    PinPWME            PinMode    = PinTimer
    PinPWMF            PinMode    = PinTimerAlt
    PinPWMG            PinMode    = PinTCCPDEC
    PinInputPulldown    PinMode    = 18
)

const (
    PA00    Pin    = 0
    PA01    Pin    = 1
    PA02    Pin    = 2
    PA03    Pin    = 3
    PA04    Pin    = 4
    PA05    Pin    = 5
    PA06    Pin    = 6
    PA07    Pin    = 7
    PA08    Pin    = 8
    PA09    Pin    = 9
    PA10    Pin    = 10
    PA11    Pin    = 11
    PA12    Pin    = 12
    PA13    Pin    = 13
    PA14    Pin    = 14
    PA15    Pin    = 15
    PA16    Pin    = 16
    PA17    Pin    = 17
    PA18    Pin    = 18
    PA19    Pin    = 19
    PA20    Pin    = 20
    PA21    Pin    = 21
    PA22    Pin    = 22
    PA23    Pin    = 23
    PA24    Pin    = 24
    PA25    Pin    = 25
    PA26    Pin    = 26
    PA27    Pin    = 27
    PA28    Pin    = 28
    PA29    Pin    = 29
    PA30    Pin    = 30
    PA31    Pin    = 31
    PB00    Pin    = 32
    PB01    Pin    = 33
    PB02    Pin    = 34
    PB03    Pin    = 35
    PB04    Pin    = 36
    PB05    Pin    = 37
    PB06    Pin    = 38
    PB07    Pin    = 39
    PB08    Pin    = 40
    PB09    Pin    = 41
    PB10    Pin    = 42
    PB11    Pin    = 43
    PB12    Pin    = 44
    PB13    Pin    = 45
    PB14    Pin    = 46
    PB15    Pin    = 47
    PB16    Pin    = 48
    PB17    Pin    = 49
    PB18    Pin    = 50
    PB19    Pin    = 51
    PB20    Pin    = 52
    PB21    Pin    = 53
    PB22    Pin    = 54
    PB23    Pin    = 55
    PB24    Pin    = 56
    PB25    Pin    = 57
    PB26    Pin    = 58
    PB27    Pin    = 59
    PB28    Pin    = 60
    PB29    Pin    = 61
    PB30    Pin    = 62
    PB31    Pin    = 63
)

Hardware pins

const (
    // SERCOM_FREQ_REF is always reference frequency on SAMD51 regardless of CPU speed.
    SERCOM_FREQ_REF    = 48000000
    // Default rise time in nanoseconds, based on 4.7K ohm pull up resistors
    riseTimeNanoseconds    = 125
    // wire bus states
    wireUnknownState    = 0
    wireIdleState        = 1
    wireOwnerState        = 2
    wireBusyState        = 3
    // wire commands
    wireCmdNoAction        = 0
    wireCmdRepeatStart    = 1
    wireCmdRead        = 2
    wireCmdStop        = 3
)

const HSRAM_SIZE = 0x00030000

Variables

var (
    I2C0 = I2C{
        Bus:    sam.SERCOM2_I2CM,
        SERCOM:    2,
    }
)

I2C on the ItsyBitsy M4.

var (
    SPI0 = SPI{
        Bus:    sam.SERCOM1_SPIM,
        SERCOM:    1,
    }
)

SPI on the ItsyBitsy M4.

var (
    ErrInvalidInputPin    = errors.New("machine: invalid input pin")
    ErrInvalidOutputPin    = errors.New("machine: invalid output pin")
    ErrInvalidClockPin    = errors.New("machine: invalid clock pin")
    ErrInvalidDataPin    = errors.New("machine: invalid data pin")
)

var (
    // UART0 is actually a USB CDC interface.
    UART0    = USBCDC{Buffer: NewRingBuffer()}
    // The first hardware serial port on the SAMD51. Uses the SERCOM3 interface.
    UART1    = UART{
        Buffer:    NewRingBuffer(),
        Bus:    sam.SERCOM3_USART_INT,
        SERCOM:    3,
        IRQVal:    sam.IRQ_SERCOM3_2,
    }
    // The second hardware serial port on the SAMD51. Uses the SERCOM0 interface.
    UART2    = UART{
        Buffer:    NewRingBuffer(),
        Bus:    sam.SERCOM0_USART_INT,
        SERCOM:    0,
        IRQVal:    sam.IRQ_SERCOM0_2,
    }
)

var (
    ErrTxInvalidSliceSize = errors.New("SPI write and read slices must be same size")
)

func CPUFrequency

func CPUFrequency() uint32

func InitADC

func InitADC()

InitADC initializes the ADC.

func InitPWM

func InitPWM()

InitPWM initializes the PWM interface.

func NewACMFunctionalDescriptor

func NewACMFunctionalDescriptor(subtype, d0 uint8) ACMFunctionalDescriptor

NewACMFunctionalDescriptor returns a new USB ACMFunctionalDescriptor.

func NewCDCCSInterfaceDescriptor

func NewCDCCSInterfaceDescriptor(subtype, d0, d1 uint8) CDCCSInterfaceDescriptor

NewCDCCSInterfaceDescriptor returns a new USB CDCCSInterfaceDescriptor.

func NewCDCDescriptor

func NewCDCDescriptor(i IADDescriptor, c InterfaceDescriptor,
    h CDCCSInterfaceDescriptor,
    cm ACMFunctionalDescriptor,
    fd CDCCSInterfaceDescriptor,
    callm CMFunctionalDescriptor,
    ci EndpointDescriptor,
    di InterfaceDescriptor,
    outp EndpointDescriptor,
    inp EndpointDescriptor) CDCDescriptor

func NewCMFunctionalDescriptor

func NewCMFunctionalDescriptor(subtype, d0, d1 uint8) CMFunctionalDescriptor

NewCMFunctionalDescriptor returns a new USB CMFunctionalDescriptor.

func NewConfigDescriptor

func NewConfigDescriptor(totalLength uint16, interfaces uint8) ConfigDescriptor

NewConfigDescriptor returns a new USB ConfigDescriptor.

func NewDeviceDescriptor

func NewDeviceDescriptor(class, subClass, proto, packetSize0 uint8, vid, pid, version uint16, im, ip, is, configs uint8) DeviceDescriptor

NewDeviceDescriptor returns a USB DeviceDescriptor.

func NewEndpointDescriptor

func NewEndpointDescriptor(addr, attr uint8, packetSize uint16, interval uint8) EndpointDescriptor

NewEndpointDescriptor returns a new USB EndpointDescriptor.

func NewIADDescriptor

func NewIADDescriptor(firstInterface, count, class, subClass, protocol uint8) IADDescriptor

NewIADDescriptor returns a new USB IADDescriptor.

func NewInterfaceDescriptor

func NewInterfaceDescriptor(n, numEndpoints, class, subClass, protocol uint8) InterfaceDescriptor

NewInterfaceDescriptor returns a new USB InterfaceDescriptor.

func NewRingBuffer

func NewRingBuffer() *RingBuffer

NewRingBuffer returns a new ring buffer.

func ResetProcessor

func ResetProcessor()

ResetProcessor should perform a system reset in preparationto switch to the bootloader to flash new firmware.

type ACMFunctionalDescriptor

type ACMFunctionalDescriptor struct {
    len        uint8
    dtype        uint8    // 0x24
    subtype        uint8    // 1
    bmCapabilities    uint8
}

ACMFunctionalDescriptor is a Abstract Control Model (ACM) USB descriptor.

func (ACMFunctionalDescriptor) Bytes

func (d ACMFunctionalDescriptor) Bytes() []byte

Bytes returns the ACMFunctionalDescriptor data.

type ADC

type ADC struct {
    Pin Pin
}

func (ADC) Configure

func (a ADC) Configure()

Configure configures a ADCPin to be able to be used to read data.

func (ADC) Get

func (a ADC) Get() uint16

Get returns the current value of a ADC pin, in the range 0..0xffff.

type CDCCSInterfaceDescriptor

type CDCCSInterfaceDescriptor struct {
    len    uint8    // 5
    dtype    uint8    // 0x24
    subtype    uint8
    d0    uint8
    d1    uint8
}

CDCCSInterfaceDescriptor is a CDC CS interface descriptor.

func (CDCCSInterfaceDescriptor) Bytes

func (d CDCCSInterfaceDescriptor) Bytes() []byte

Bytes returns CDCCSInterfaceDescriptor data.

type CDCDescriptor

type CDCDescriptor struct {
    //    IAD
    iad    IADDescriptor    // Only needed on compound device
    //    Control
    cif    InterfaceDescriptor
    header    CDCCSInterfaceDescriptor
    // CDC control
    controlManagement    ACMFunctionalDescriptor        // ACM
    functionalDescriptor    CDCCSInterfaceDescriptor    // CDC_UNION
    callManagement        CMFunctionalDescriptor        // Call Management
    cifin            EndpointDescriptor
    //    CDC Data
    dif    InterfaceDescriptor
    in    EndpointDescriptor
    out    EndpointDescriptor
}

CDCDescriptor is the Communication Device Class (CDC) descriptor.

func (CDCDescriptor) Bytes

func (d CDCDescriptor) Bytes() []byte

Bytes returns CDCDescriptor data.

type CMFunctionalDescriptor

type CMFunctionalDescriptor struct {
    bFunctionLength        uint8
    bDescriptorType        uint8    // 0x24
    bDescriptorSubtype    uint8    // 1
    bmCapabilities        uint8
    bDataInterface        uint8
}

CMFunctionalDescriptor is the functional descriptor general format.

func (CMFunctionalDescriptor) Bytes

func (d CMFunctionalDescriptor) Bytes() []byte

Bytes returns the CMFunctionalDescriptor data.

type ConfigDescriptor

type ConfigDescriptor struct {
    bLength            uint8    // 9
    bDescriptorType        uint8    // 2
    wTotalLength        uint16    // total length
    bNumInterfaces        uint8
    bConfigurationValue    uint8
    iConfiguration        uint8
    bmAttributes        uint8
    bMaxPower        uint8
}

ConfigDescriptor implements the standard USB configuration descriptor.

Table 9-10. Standard Configuration DescriptorbLength, bDescriptorType, wTotalLength, bNumInterfaces, bConfigurationValue, iConfigurationbmAttributes, bMaxPower

func (ConfigDescriptor) Bytes

func (d ConfigDescriptor) Bytes() []byte

Bytes returns ConfigDescriptor data.

type DeviceDescriptor

type DeviceDescriptor struct {
    bLength            uint8    // 18
    bDescriptorType        uint8    // 1 USB_DEVICE_DESCRIPTOR_TYPE
    bcdUSB            uint16    // 0x200
    bDeviceClass        uint8
    bDeviceSubClass        uint8
    bDeviceProtocol        uint8
    bMaxPacketSize0        uint8    // Packet 0
    idVendor        uint16
    idProduct        uint16
    bcdDevice        uint16    // 0x100
    iManufacturer        uint8
    iProduct        uint8
    iSerialNumber        uint8
    bNumConfigurations    uint8
}

DeviceDescriptor implements the USB standard device descriptor.

Table 9-8. Standard Device DescriptorbLength, bDescriptorType, bcdUSB, bDeviceClass, bDeviceSubClass, bDeviceProtocol, bMaxPacketSize0, idVendor, idProduct, bcdDevice, iManufacturer, iProduct, iSerialNumber, bNumConfigurations */

func (DeviceDescriptor) Bytes

func (d DeviceDescriptor) Bytes() []byte

Bytes returns DeviceDescriptor data

type EndpointDescriptor

type EndpointDescriptor struct {
    bLength            uint8    // 7
    bDescriptorType        uint8    // 5
    bEndpointAddress    uint8
    bmAttributes        uint8
    wMaxPacketSize        uint16
    bInterval        uint8
}

EndpointDescriptor implements the standard USB endpoint descriptor.

Table 9-13. Standard Endpoint DescriptorbLength, bDescriptorType, bEndpointAddress, bmAttributes, wMaxPacketSize, bInterval

func (EndpointDescriptor) Bytes

func (d EndpointDescriptor) Bytes() []byte

Bytes returns EndpointDescriptor data.

type I2C

type I2C struct {
    Bus    *sam.SERCOM_I2CM_Type
    SERCOM    uint8
}

I2C on the SAMD51.

func (I2C) Configure

func (i2c I2C) Configure(config I2CConfig) error

Configure is intended to setup the I2C interface.

func (I2C) ReadRegister

func (i2c I2C) ReadRegister(address uint8, register uint8, data []byte) error

ReadRegister transmits the register, restarts the connection as a readoperation, and reads the response.

Many I2C-compatible devices are organized in terms of registers. This methodis a shortcut to easily read such registers. Also, it only works for deviceswith 7-bit addresses, which is the vast majority.

func (I2C) SetBaudRate

func (i2c I2C) SetBaudRate(br uint32)

SetBaudRate sets the communication speed for the I2C.

func (I2C) Tx

func (i2c I2C) Tx(addr uint16, w, r []byte) error

Tx does a single I2C transaction at the specified address.It clocks out the given address, writes the bytes in w, reads back len®bytes and stores them in r, and generates a stop condition on the bus.

func (I2C) WriteByte

func (i2c I2C) WriteByte(data byte) error

WriteByte writes a single byte to the I2C bus.

func (I2C) WriteRegister

func (i2c I2C) WriteRegister(address uint8, register uint8, data []byte) error

WriteRegister transmits first the register and then the data to theperipheral device.

Many I2C-compatible devices are organized in terms of registers. This methodis a shortcut to easily write to such registers. Also, it only works fordevices with 7-bit addresses, which is the vast majority.

type I2CConfig

type I2CConfig struct {
    Frequency    uint32
    SCL        Pin
    SDA        Pin
}

I2CConfig is used to store config info for I2C.

type I2SClockSource

type I2SClockSource uint8

type I2SConfig

type I2SConfig struct {
    SCK            Pin
    WS            Pin
    SD            Pin
    Mode            I2SMode
    Standard        I2SStandard
    ClockSource        I2SClockSource
    DataFormat        I2SDataFormat
    AudioFrequency        uint32
    MasterClockOutput    bool
    Stereo            bool
}

All fields are optional and may not be required or used on a particular platform.

type I2SDataFormat

type I2SDataFormat uint8

type I2SMode

type I2SMode uint8

type I2SStandard

type I2SStandard uint8

type IADDescriptor

type IADDescriptor struct {
    bLength            uint8    // 8
    bDescriptorType        uint8    // 11
    bFirstInterface        uint8
    bInterfaceCount        uint8
    bFunctionClass        uint8
    bFunctionSubClass    uint8
    bFunctionProtocol    uint8
    iFunction        uint8
}

IADDescriptor is an Interface Association Descriptor, which is usedto bind 2 interfaces together in CDC composite device.

Standard Interface Association Descriptor:bLength, bDescriptorType, bFirstInterface, bInterfaceCount, bFunctionClass, bFunctionSubClass,bFunctionProtocol, iFunction

func (IADDescriptor) Bytes

func (d IADDescriptor) Bytes() []byte

Bytes returns IADDescriptor data.

type InterfaceDescriptor

type InterfaceDescriptor struct {
    bLength            uint8    // 9
    bDescriptorType        uint8    // 4
    bInterfaceNumber    uint8
    bAlternateSetting    uint8
    bNumEndpoints        uint8
    bInterfaceClass        uint8
    bInterfaceSubClass    uint8
    bInterfaceProtocol    uint8
    iInterface        uint8
}

InterfaceDescriptor implements the standard USB interface descriptor.

Table 9-12. Standard Interface DescriptorbLength, bDescriptorType, bInterfaceNumber, bAlternateSetting, bNumEndpoints, bInterfaceClass,bInterfaceSubClass, bInterfaceProtocol, iInterface

func (InterfaceDescriptor) Bytes

func (d InterfaceDescriptor) Bytes() []byte

Bytes returns InterfaceDescriptor data.

type MSCDescriptor

type MSCDescriptor struct {
    msc    InterfaceDescriptor
    in    EndpointDescriptor
    out    EndpointDescriptor
}

MSCDescriptor is not used yet.

type PWM

type PWM struct {
    Pin Pin
}

func (PWM) Configure

func (pwm PWM) Configure()

Configure configures a PWM pin for output.

func (PWM) Set

func (pwm PWM) Set(value uint16)

Set turns on the duty cycle for a PWM pin using the provided value.

type Pin

type Pin int8

Pin is a single pin on a chip, which may be connected to other hardwaredevices. It can either be used directly as GPIO pin or it can be used inother peripherals like ADC, I2C, etc.

func (Pin) Configure

func (p Pin) Configure(config PinConfig)

Configure this pin with the given configuration.

func (Pin) Get

func (p Pin) Get() bool

Get returns the current value of a GPIO pin.

func (Pin) High

func (p Pin) High()

High sets this GPIO pin to high, assuming it has been configured as an outputpin. It is hardware dependent (and often undefined) what happens if you set apin to high that is not configured as an output pin.

func (Pin) Low

func (p Pin) Low()

Low sets this GPIO pin to low, assuming it has been configured as an outputpin. It is hardware dependent (and often undefined) what happens if you set apin to low that is not configured as an output pin.

func (Pin) PortMaskClear

func (p Pin) PortMaskClear() (*uint32, uint32)

Return the register and mask to disable a given port. This can be used toimplement bit-banged drivers.

func (Pin) PortMaskSet

func (p Pin) PortMaskSet() (*uint32, uint32)

Return the register and mask to enable a given GPIO pin. This can be used toimplement bit-banged drivers.

func (Pin) Set

func (p Pin) Set(high bool)

Set the pin to high or low.Warning: only use this on an output pin!

func (Pin) Toggle

func (p Pin) Toggle()

Toggle switches an output pin from low to high or from high to low.Warning: only use this on an output pin!

type PinConfig

type PinConfig struct {
    Mode PinMode
}

type PinMode

type PinMode uint8

type RingBuffer

type RingBuffer struct {
    rxbuffer    [bufferSize]volatile.Register8
    head        volatile.Register8
    tail        volatile.Register8
}

RingBuffer is ring buffer implementation inspired by post athttps://www.embeddedrelated.com/showthread/comp.arch.embedded/77084-1.php

It has some limitations currently due to how “volatile” variables that aremembers of a struct are not compiled correctly by TinyGo.See https://github.com/tinygo-org/tinygo/issues/151 for details.

func (*RingBuffer) Get

func (rb *RingBuffer) Get() (byte, bool)

Get returns a byte from the buffer. If the buffer is empty,the method will return a false as the second value.

func (*RingBuffer) Put

func (rb *RingBuffer) Put(val byte) bool

Put stores a byte in the buffer. If the buffer is alreadyfull, the method will return false.

func (*RingBuffer) Used

func (rb *RingBuffer) Used() uint8

Used returns how many bytes in buffer have been used.

type SPI

type SPI struct {
    Bus    *sam.SERCOM_SPIM_Type
    SERCOM    uint8
}

SPI

func (SPI) Configure

func (spi SPI) Configure(config SPIConfig) error

Configure is intended to setup the SPI interface.

func (SPI) Transfer

func (spi SPI) Transfer(w byte) (byte, error)

Transfer writes/reads a single byte using the SPI interface.

func (SPI) Tx

func (spi SPI) Tx(w, r []byte) error

Tx handles read/write operation for SPI interface. Since SPI is a syncronous write/readinterface, there must always be the same number of bytes written as bytes read.The Tx method knows about this, and offers a few different ways of calling it.

This form sends the bytes in tx buffer, putting the resulting bytes read into the rx buffer.Note that the tx and rx buffers must be the same size:

    spi.Tx(tx, rx)

This form sends the tx buffer, ignoring the result. Useful for sending “commands” that return zerosuntil all the bytes in the command packet have been received:

    spi.Tx(tx, nil)

This form sends zeros, putting the result into the rx buffer. Good for reading a “result packet”:

    spi.Tx(nil, rx)

type SPIConfig

type SPIConfig struct {
    Frequency    uint32
    SCK        Pin
    MOSI        Pin
    MISO        Pin
    LSBFirst    bool
    Mode        uint8
}

SPIConfig is used to store config info for SPI.

type UART

type UART struct {
    Buffer    *RingBuffer
    Bus    *sam.SERCOM_USART_INT_Type
    SERCOM    uint8
    IRQVal    uint32    // RXC interrupt
}

UART on the SAMD51.

func (UART) Buffered

func (uart UART) Buffered() int

Buffered returns the number of bytes currently stored in the RX buffer.

func (UART) Configure

func (uart UART) Configure(config UARTConfig) error

Configure the UART.

func (UART) Read

func (uart UART) Read(data []byte) (n int, err error)

Read from the RX buffer.

func (UART) ReadByte

func (uart UART) ReadByte() (byte, error)

ReadByte reads a single byte from the RX buffer.If there is no data in the buffer, returns an error.

func (UART) Receive

func (uart UART) Receive(data byte)

Receive handles adding data to the UART’s data buffer.Usually called by the IRQ handler for a machine.

func (UART) SetBaudRate

func (uart UART) SetBaudRate(br uint32)

SetBaudRate sets the communication speed for the UART.

func (UART) Write

func (uart UART) Write(data []byte) (n int, err error)

Write data to the UART.

func (UART) WriteByte

func (uart UART) WriteByte(c byte) error

WriteByte writes a byte of data to the UART.

type UARTConfig

type UARTConfig struct {
    BaudRate    uint32
    TX        Pin
    RX        Pin
}

type USBCDC

type USBCDC struct {
    Buffer *RingBuffer
}

USBCDC is the USB CDC aka serial over USB interface on the SAMD21.

func (USBCDC) Buffered

func (usbcdc USBCDC) Buffered() int

Buffered returns the number of bytes currently stored in the RX buffer.

func (USBCDC) Configure

func (usbcdc USBCDC) Configure(config UARTConfig)

Configure the USB CDC interface. The config is here for compatibility with the UART interface.

func (USBCDC) DTR

func (usbcdc USBCDC) DTR() bool

func (USBCDC) RTS

func (usbcdc USBCDC) RTS() bool

func (USBCDC) Read

func (usbcdc USBCDC) Read(data []byte) (n int, err error)

Read from the RX buffer.

func (USBCDC) ReadByte

func (usbcdc USBCDC) ReadByte() (byte, error)

ReadByte reads a single byte from the RX buffer.If there is no data in the buffer, returns an error.

func (USBCDC) Receive

func (usbcdc USBCDC) Receive(data byte)

Receive handles adding data to the UART’s data buffer.Usually called by the IRQ handler for a machine.

func (USBCDC) Write

func (usbcdc USBCDC) Write(data []byte) (n int, err error)

Write data to the USBCDC.

func (USBCDC) WriteByte

func (usbcdc USBCDC) WriteByte(c byte) error

WriteByte writes a byte of data to the USB CDC interface.